[05] WHEN AND HOW ARE ACCOUNTS EXPIRED?
 
     user (both prevalidated and validated) accounts are the only login
     accounts subject to automated purges.  These purges occur monthly and
     are based on your last UNIX login time if you are validated, or the
     number of days since your account was created if you are prevalidated.

     Prevalidated accounts are automatically purged whether they are in
     use or not approximately 600 days of their creation.  Validated accounts
     will expire if the user does not login at least once during a 2 year
     period.

     ARPA members are exempt from inactivity purges, though an ARPA member
     may lose their membership by violating the AUP.  When disk space becomes
     an issue, ARPA members who have not logged in for 1 year or longer may
     have their files compressed.  No files will be deleted and the user is
     welcome to login an uncompress files as needed.  

     Keep in mind that using SDF for only webmail or pop3/imap service does
     not log you in to the UNIX system. You will have to login to the shell
     account regularly to avoid being flagged as an inactive account.
